Water and Temperature Stresses Impact Canola (Brassica napus L

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Water and Temperature Stresses Impact Canola (Brassica napus L.) Fatty Acid, Protein and Yield over Nitrogen and Sulfur W. Ashley Hammac, Tai Maaz, Richard T. Koenig, Ian C. Burke, and William L. Pan J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.7b02778 • Publication Date (Web): 07 Nov 2017 Downloaded from http://pubs.acs.org on November 7, 2017

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Journal of Agricultural and Food Chemistry

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Water and Temperature Stresses Impact Canola (Brassica napus L.) Fatty Acid, Protein and Yield over

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Nitrogen and Sulfur

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W. Ashley Hammac,*†‡ Tai M. Maaz,‡§ Richard T. Koenig,‡ Ian C. Burke,‡ and William L. Pan‡ †

USDA, Agriculture Research Service, National Soil Erosion Research Lab, 275 South Russell St., West Lafayette, Indiana, 47907, USA ‡ Washington State University, PO Box 646420, Pullman, Washington 99164-6420, USA § International Plant Nutrition Institute, 3500 Parkway Lane, Suite 550, Peachtree Corners, Georgia 30092-2844, USA *(765)494-8697 [email protected]

ACS Paragon Plus Environment


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Abstract Interactive effects of weather and soil nutrient status often control crop productivity. An

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experiment was conducted to determine effects of nitrogen (N) and sulfur (S) fertilizer rate, soil water,

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and atmospheric temperature on canola (Brassica napus L.) fatty acid (FA), total oil, protein and grain

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yield. Nitrogen and S were assessed in a 4-yr study with two locations, five N rates (0, 45, 90, 135 and

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180 kg ha-1) and two S rates (0 and 17 kg ha-1). Water and temperature were assessed using variability

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across 12 site-years of dryland canola production. Effects of N and S were inconsistent. Unsaturated FA,

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oleic acid, grain oil, protein and theoretical maximum grain yield were highly related to water and

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temperature variability across the site-years. A non-linear model identified water and temperature

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conditions that enabled production of maximum unsaturated FA content, oleic acid content, total oil,

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protein and theoretical maximum grain yield. Water and temperature variability played a larger role

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than soil nutrient status on canola grain constituents and yield.

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Keywords: canola, fatty acid, protein, oil, soil, water, temperature, stress


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Introduction Canola or oilseed rape (Brassica napus L.) has high yield potential for oil and protein meal across

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the globe where it is adapted to diverse agro-climatic conditions. In the U.S., the crop is adapted to

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semi-arid dryland conditions and is grown with existing wheat farming equipment circumventing the

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need for major investments. Other benefits of canola cultivation include increased diversification of

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cropping systems for improved food security and cropping system resiliency,1 potential increased supply

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of high quality edible oil for human consumption and animal feed to supply local dairies,2 and expansion

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of rural economies through development of regional oil and biodiesel processing units.3 Canola may also

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mitigate greenhouse gas emissions as a biofuel feedstock and facilitate control of grassy weeds that are

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problematic in cereal production systems. To produce healthy edible oil, biofuels and quality protein

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feed, agriculture professionals must understand the relationship between soil nutrient management and

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environmental stress related to available water and atmospheric temperature.

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Environmental stress has a tremendous effect on crop productivity and consequently on food

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availability and the agricultural economy.4 Although brassica crops are well-suited for production in

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semi-arid environments,5 significant variability occurs in plant productivity and oil composition as a

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result of weather variability.6-12 Both laboratory and field studies have indicated a pronounced negative

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effect of water deficit on canola productivity and on soil N availability in arid or semi-arid

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environments.13-16 Nitrogen requirement of canola is highly variable across spatial and temporal

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gradients and can range from 3.9 to 11 kg N per 100 kg seed yield based on growing season (winter or

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spring) and numerous other factors.7, 17 Variable yield potential of non-N limited systems as defined by

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Mitscherlich relationships demonstrates that soil moisture dictates yield potential in rain-fed semi-arid

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regions.18 However, until recently Mitscherlich N responses were only inherently linked to stress related

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to water availability, contained in the “A” parameter also known as theoretical maximum yield. More

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recent work added that in semi-arid regions, N requirement differs spatially due to not only soils, etc.,



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but also temporally due to year-to-year fluctuations in available soil moisture.15 Environmental stress is

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reported to affect oil constituents. Some researchers have reported decreased amounts of linoleic acid

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(C18:2 cis,cis-9,12-octadecadienoic acid) and increased amounts of oleic acid (C18:1, cis-9-octadecenoic

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acid) with increasing levels of drought, 19 whereas, others have observed a quadratic response in canola

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oleic acid with increasing available water.20 The effects of water deficit on physiological processes

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related to lipid biosynthesis are not fully understood, but water deficit affects embryo development and

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enzyme activity (including lipid biosynthesis enzymes).19 In addition, water deficit limits CO2 assimilation

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due to restricted stomatal conductance slowing sugar absorption into embryos. The hydrologic changes

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resulting from climate change may thus have a decisive effect on oil content, oil composition, grain

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protein and grain yield. This underlines the need to understand interactions between soil nutrient status

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and environmental variability.

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Atmospheric temperature has a significant effect on canola germination, vernalization, biomass

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production, growth rate, duration, fall establishment, winter survival, seed mass, grain yield, oil quantity

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and quality, and grain protein.7, 12, 21 In a multi-crop experiment, it was determined that increasing

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atmospheric temperature decreased total oil, increased protein, increased oleic acid, and decreased

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erucic acid (C22:1 cis-9-docosenoic acid) for oilseed rape.22 Because of successful crop breeding, erucic

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acid - an undesirable FA for human and animal consumption - is no longer a major component of

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modern rapeseed varieties or canola largely due to replacement of erucic acid by oleic acid.22-25 Across

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14 low rainfall environments in southern Australia, maximum growing season atmospheric temperature

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was positively correlated with linolenic acid (C18:3 cis,cis,cis-9,12,15-octadecatrienoic acid), total oil and

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protein while average maximum growing season atmospheric temperature was negatively correlated

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with oleic acid and saturated FA.20 In the same study, average minimum growing season atmospheric

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temperature was positively correlated with linolenic acid and total oil while average minimum growing

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season atmospheric temperature was negatively correlated with saturated FA and protein.


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Multicollinearity is often observed for grain oil and protein, as well as for oil composition for a single

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explanatory variable and thus a tradeoff often exists when maximizing either oil or protein fraction or

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yield. Protein and oil together account for only 60% of total seed mass leaving 40% as soluble and

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complex carbohydrates, phenolics and isothiocyanates, suggesting that it is plausible to simultaneously

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increase protein and oil. However, available evidence indicated that higher atmospheric temperature

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increases grain protein while simultaneously decreasing grain oil.20-21 There are several mechanisms

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related to the influence of soil water on plant productivity in Mediterranean climates. Among them is a

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strong correlation between N mineralization and soil water indicating the complex interaction needing

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further investigation.15 In the semi-arid dryland inland Pacific Northwest, high temperature and water

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stress are projected to increase during the growing season,26 thus requiring researchers to understand

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crop responses to facilitate adaptation, particularly as it relates to soil nutrient management.

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Nitrogen plant nutritional requirements and soil N dynamics are well known and are described

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in detail in modern agricultural research.27-30 However, N mobility, in addition to soil and climate

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variability, obscure crop responses to N fertility. Nitrogen use efficiency (NUE) (i.e. grain yield per unit N

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supply) has been well defined,31 and for brassicas is related to many environmental factors.7 Most

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limiting growth factors, as defined by Liebig’s law of the minimum, are responsible for reducing NUE and

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many are stochastic in nature. Some however, are controllable (e.g. less or non-mobile plant nutrients)

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and must be maximized to prevent an antagonistic plant response. For example, in a 14 site-year field

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experiment, hybrid canola outperformed open pollinated varieties and scavenged more residual

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nutrients when N, P and S fertility was also adequate.32 However, maximizing nutrient availability to

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ensure non-limiting status can cause additional problems due to overabundance (e.g. P and surface

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water quality).33-34 Currently in canola production, farmers apply N fertilizer to maximize seed yield.

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However, there is a need to consider the influence of N on oil content and quality while attempting to

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maximize oil yield and quality.



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Much of the S taken up by canola is transported to the seed.25 In addition to being a component

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of methionine and cysteine, S is a component of glucosinolate, a member of the isothiocyanate

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compound family and historically abundant in brassicas.25, 27 However, canola, by definition, has

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extremely low levels of glucosinolate for food and feed quality purposes. Sulfur is also a component of

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sulfolipids, which are only contained in the chloroplast membrane.25, 27 Clean air regulations, increased S

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removal by crops and less S in N and P fertilizers, has potentially lowered soil S levels requiring that

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more attention be paid to soil S levels.35 This coincides with a growing trend of positive yield responses

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to applied S.36 Since canola has more affinity for S than cereals, the potential of S deficiency is becoming

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more of a concern.35, 37 While excessive N decreases seed oil fraction, increased S fertility increases oil

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fraction.37-40 Early work noted excessive S decreased oil fraction but the rise in grain yield more than

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compensated for the loss in oil fraction in most cases.41

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In this study, our objectives were to 1) determine the interactive effect of available soil water

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and atmospheric temperature on canola FA composition, oil content, protein content and grain yield at

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the economic optimum N rate (EONR), 2) develop a “water and temperature” parameter for the

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Mitscherlich equation that replaces the “theoretical maximum yield” parameter and 3) determine the

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effect of N and S on canola oil composition, grain protein and grain yield.

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Materials and Methods

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Site and Sampling Description

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Field experiments were conducted at two locations affiliated with Washington State University

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(WSU) from 2008 to 2013. Each location has different environmental characteristics, but both are

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categorized as Mediterranean-like climates (Tables 1 and 2). We conducted the experiments at the

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WSU/USDA Palouse Conservation Field Station near Pullman, WA and the WSU Wilke Farm near

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Davenport, WA. Pre-season composite soil samples were taken with a hydraulic soil probe (Giddings


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Machine Company Inc., Windsor, CO) in 30 cm increments to 120 cm depth to determine baseline soil

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nutrient status.

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Crop Management

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Nutrient deficiencies aside from N and S were corrected on a site-year basis according to soil

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test results (Table 2). Roundup® ready canola was seeded at a rate of 8 kg ha-1 at both sites with a

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Fabro® direct seed plot drill. Planting timing, variety, preceding crop and harvest timing varied by year

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and location (Table 3). Fall sown (winter) canola was grown in 2008-2009, but spring canola was grown

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for all other site-years. Triple super phosphate (TSP) (46% P) and potassium chloride (KCl) (60% K) were

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applied when necessary to correct P and K deficiency. Glyphosate [N-(phosphonomethyl)glycine] was

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used at a rate of 0.6 L ha-1 to control weeds before planting and glyphosate and manual removal was

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utilized for in-season weed control.

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Experimental Design

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Plots were 2.3 m in width and 15.2 m length (34.7 m2) and arranged in a randomized complete

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block design with treatments consisting of a five N rates (0 to 180 kg N ha-1 in 45 kg increments),

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replicated four times. Urea [CO(NH2)2] (46% N) and ammonium sulfate [(NH4)2SO4] (21% N and 24% S)

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fertilizers were banded 7.5 to 10 cm beneath the surface to supply N. Nitrogen timing was assessed in

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years 2008, 2009 and 2010. Each N treatment was applied either in fall, spring or both fall and spring.

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Grain yield response to N timing and S were not significant effects for each site-year, so data for the

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same total N rate treatments were pooled and used to generate N supply response curves. Plot borders

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were trimmed to minimize edge effect on yield and canola was harvested using a plot combine (Kincaid

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Equipment Manufacturing, Haven, KS).

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Grain Analysis

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After harvest, seed was re-cleaned using a 2 mm sieve, air-dried and weighed to determine yield for the trimmed harvest area. Grain oil content was determined using a nuclear magnetic resonance



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analyzer (Newport MK III-A, Oxford Analytical Instruments Ltd., Andover, MA). Total grain N was

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determined with a CN analyzer (TruSpec, LECO Corp., Saint Joseph, MI) and N percentage was multiplied

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by 5.53 to calculate protein percentage.42 Fatty acid composition was determined using a gas

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chromatograph (5890 Series II, Hewlett-Packard Co., Wilmington, DE). Grain chemistry characteristics

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were determined for grain samples at or near the EONR. We fit grain yield response to N supply using

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the Mitscherlich equation:

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Y = A*1-exp [-C(X+B)]

[1]

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where Y is measured yield, A is theoretical maximum yield (i.e. Y-asymptote); C is the efficiency factor

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(i.e. initial slope); X is applied N fertilizer; and B is the sum of residual soil N, estimated mineralized N,

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and seed N. We determined total available water by the following equation:

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H2Ot = H2Os + H2Op

[2]

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where H2Ot is total available water, H2Os is pre-plant soil test root zone water down to a 120 cm depth

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and H2Op is precipitation between pre-plant soil test and grain harvest. To quantify high temperature

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stress for the canola crop, we first estimated the time during which plants were susceptible to heat

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stress by determining growing degree days and flowering period.43 The method for estimating flowering

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period was verified for four of 12 site-years (2010 and 2011). Once flowering period was determined,

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high temperature stress was determined by counting days where the maximum temperature reached

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28°C or above as this has shown to decrease yield and affect FA profile in canola.21 The new variable is

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referred to as temperature stress during flowering (TSDF) and was measured in days. It was then

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combined with H2Ot in a 2-variable, non-linear model and used it to predict unsaturated FA, oleic acid,

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total oil, protein or Mitscherlich theoretical maximum yield:

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Z = A*exp|-0.5*[( H2Ot -X0)/B]^2 + [(TSDF-Y0)/C]^2|


[3]

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where Z is total unsaturated FA, oleic acid, total oil, protein, or Mitscherlich theoretical maximum yield;

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A is the theoretical Z-maxima; X0 is the X-intercept; B is the efficiency factor for H2Ot; Y0 is the Y-

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intercept; and C is the efficiency factor for TSDF.

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Statistical Analysis

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For both models (Equations [2] and [3]), least squares fit was done by fitting predicted values

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with real data and adjusting coefficients using the SAS NLIN procedure (SAS Institute, Cary, NC). For the

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2-variable models (Equation [3]), the adjusted coefficient of multiple determination (adjusted R2) is

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reported to give a more conservative estimation of goodness of fit due to having multiple regressors. To

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assess statistical differences in unsaturated FA, total oil content, protein and grain yield response to N

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and S fertility, data were analyzed using the SAS GLM procedure (SAS Institute, Cary, NC).

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Results and Discussion

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Water and Temperature Effect on Grain Chemistry

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Total available water and temperature during flowering had a marked effect on total

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unsaturated FA, oleic acid, total oil, protein and grain yield (Table 4). Water deficit magnitude, duration

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and timing with growth stage have been previously observed to affect seed mass, oil and protein

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content across many species.10, 19 In rapeseed, lipid biosynthesis is sensitive to water deficit during late

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flowering and increases oleic acid production at the expense of linolenic and erucic acids, but varies by

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cultivar.44 Temperature stress, particularly during flowering also affects canola seed yield.10-12 Female

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and male sterility due to abnormal gynoecia and microspore development are two mechanisms by

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which heat stress can cause flower abortion (flower blast) and reduce pod number, seed count and

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ultimately seed yield in canola.45-46 However, since canola is somewhat compensatory due to its

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indeterminate growth habit, it can recover from a short period of heat stress.21 Taking advantage of this

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trait as well as breeding for earlier flowering and cold tolerant winter varieties are approaches that have

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promise for adaptation to temperature stress.6



Most of the site-year variability in total unsaturated FA was explained by H2Ot and TSDF

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(adjusted R2 = 0.94) (Figure 1). Oleic acid content, which is of interest to canola oil producers, also

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correlated well with H2Ot and TSDF (adjusted R2 = 0.57) (Figure 2). Previous studies have shown that

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water deficit during early vegetative, flowering and seed fill stages has the most dramatic effects on

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rapeseed seed chemistry (FA, protein, phenolic and glucosinolate) except for soluble carbohydrates,

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which amount to about 10% of total seed mass.44, 47 In this study, water limitation resulted in increased

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seed oleic acid and decreased linoleic acid content, which is consistent with earlier reported studies.19

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High temperature decreased total unsaturated FA content, but there appears to be an optimal range for

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both water and temperature stress for maximum oleic acid content. However, some researchers have

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found high temperature to increase oleic acid content when static controlled temperatures were

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examined.21 In a study on the effect of temperature on high erucic acid rapeseed, the author found

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erucic acid to have an optimum temperature, while oleic acid had a response that was inverse to erucic

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acid.22

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Variations in total oil content (adjusted R2 = 0.57) and protein (adjusted R2 = 0.72) were well

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explained by TSDF and H2Ot in the non-linear form (Figures 3 and 4). Increasing temperature stress

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decreased oil content to a much greater degree than previously cited in a regional scale assessment, but

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increased protein content (Figure 5) as these two grain constituents are often inversely related.19, 21-22

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Previous work indicated that higher night temperature in early stage canola leads to lower seed oil

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concentration whereas in late stage canola, high temperature leads to lower seed yield due to pollen

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sterilization.19 Higher temperature could increase N bioavailability, causing more amino acid assimilation

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and less C to be available for lipid biosynthesis.19 Total oil and protein behaved differently in relation to

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water stress. An increase in water stress correlated with an increase in total oil, whereas there was an

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optimum level of water stress for maximum protein content. Thus, total oil and protein content are not


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always inversely related and there are apparently other grain constituents, which contribute in the

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balance between grain oil and protein.

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Previously, we determined that total available water alone accounted for 45% of canola grain

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yield variability in these field experiments.14 The model containing H2Ot and TSDF (Equation [3])

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accounted for 64% of site-year variability for Mitscherlich theoretical maximum grain yield (adjusted R2

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= 0.64) (Figure 6). Water deficit during flowering and seed set reduces seed number, while deficit during

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seed fill reduces seed size.10, 19

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Nitrogen and Sulfur Impact on Protein and Fatty Acid Composition

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Over the entire experiment (n = 320), percent seed protein and percent seed oil were negatively

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correlated (R2 = -0.69); however, individual site-years did not always follow this pattern (Figure 5). For

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site-years where there were grain yield responses to N or S, there was a larger spread in seed protein

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and oil. When little or no N or S response was present, seed protein and oil were less correlated. There

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was no correlation between seed oil content and N supply (soil test N, seed N, expected mineralized N

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and fertilizer N) (R2 = -0.04). There was no apparent relationship between canola grain yield and soil N:S

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ratio, canola grain yield and percent seed oil, or N:S ratio and percent seed oil. There was a positive

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relationship between canola grain yield and oil yield but no apparent relationship between N:S ratio and

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oil yield.

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Though some researchers have found weak relationships between soil nutrient status and

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canola FA composition, there has been no clear connection reported in the literature.48-51 In a canola

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study investigating N fertilizers and manure, researchers found that N fertilizer did not always affect FA

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composition in the same manner and FA composition varied more by site-year than by treatment.51 The

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authors noted that increasing N fertilizer increased saturated oil and decreased the ratio of

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monounsaturated to polyunsaturated oils, but others found that rapeseed FA composition was

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“marginally influenced” by N and S fertilizer.50



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Similar relationships were observed in the present study. The impact of N and S fertility on FA

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composition was often statistically significant, but perhaps not practically significant. Fatty acid

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composition varied more by site-year than by N and S. There were no differences in FA composition

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owing to the main effects, N rate (linear or quadratic), S rate, or N rate x S rate interaction when looking

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across all site-years. Location (P < 0.0001) and year (P < 0.0001) significantly affected FA composition

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and there was a significant N rate x S rate x site-year interaction for FA composition (P < 0.0001). So, N

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and S rate effects were assessed by individual year and location for total unsaturated FA (oleic acid,

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linoleic acid and linolenic acid) (Table 5). Previous studies have found that in-season ambient

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atmospheric temperature in soybean (Glycine max L.) and available water in sunflower (Helianthus

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annuus L.) are the likely causes of the major site-year differences in FA composition.48, 52-53

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Across all site-years, the range in oleic acid differed by almost 4%, whereas within site-year

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variation due to fertility treatments were no larger than 1.6%, and for most site-years the differences

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were smaller than 1%. Addition of N and S raised oleic acid percentages in three site-years. Linoleic acid

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and linolenic acid percentages responded conversely to oleic acid with both N and S when changes were

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observed.

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Oleic, linoleic and linolenic acids comprised approximately 88% of total FAs present in this

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experiment, which are superior for both food and feed value. It appears N or S fertility will have little

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effect on biodiesel fuel quality. However, site-year (i.e. soil and weather variability) may have a

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significant effect since higher degree of unsaturation improves cold temperature fuel performance, but

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degrades fuel lines and increases NOx (NO(g)+NO2(g)) emissions.54-55 Some European countries have

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adopted a standard that biodiesel feedstock oil iodine value (a method for determining degree of

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unsaturation) should be below 115.56 The typical iodine value range for canola oil is on either side of this

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range (110-126), but the iodine value of rapeseed oil with high erucic acid content falls below 115 (97-

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108).57 This distinction may be important for developing specific food- and fuel-grade oilseed markets.


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There were no differences in grain protein owing to the main effects, N rate (linear or

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quadratic), S rate, or N rate x S rate interaction when looking across all site-years (Table 6). There were

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differences owing to main effects when looking at effects by site-year; however, those responses

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corresponded with significant interactions in the same site-year. In every instance where there was a

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significant effect, the effect was positively related to N or S rate. In three of four site-years where a

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significant N x S interaction was present, the 180 kg ha-1 N rate and the 0 kg ha-1 S rate yielded the most

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protein. In two site-years, the 180-0 and 180-17 N-S rates were not different and in one site-year, 180-

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17 yielded more protein than 180-0. Positive N and S fertilizer effects have been previously detected for

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percent seed protein in canola, which corresponded to a negative N fertilizer response for percent seed

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oil and inconsistent effect of S fertilizer on oil.49 Others have reported that S fertilizer had no impact on

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wheat yield or protein.58 Increasing N fertilizer rate generally increased Ethiopian mustard (Brassica

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carinata) grain yield and grain protein, and decreased grain oil.59

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In the present study, high levels of residual soil N status diluted responses to N fertilizer to a

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large degree likely due to insertion of a fallow rotation prior to canola thus allowing for N mineralization.

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Likewise, soil S levels were not extremely low, so a response to S would be muted particularly in years of

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unfavorable growing conditions. The findings thus suggest that grain and oil yield and oil quality are

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more responsive to environmental factors like temperature and available water than soil nutrient status.

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This highlights the need to educate farmers to apply nutrients, especially N, on an average economic

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optimum rate basis since much of the variability in yield is uncontrollable. Applying N on the basis of

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yield potential under ideal conditions may result in frequent over-application. Additionally, cropping

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system management that improves water infiltration and soil water-holding capacity, like soil surface

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residue cover and soil organic matter may provide resiliency when weather is unfavorable. Timely

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planting of spring canola is a critical factor and can interact with nutrient uptake and plant productivity.

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Sufficient S may not be problematic in dryland cereal production areas since wheat requires more S than



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canola. Fatty acid composition may not be influenced much by N and S but feed and fuel processors

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should be cognizant of weather effects on FA composition.

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Nitrogen and Sulfur Rate Effect on Oil Content and Grain Yield There were significant N rate x site-year and S rate x site-year interactions for both grain yield (P

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< 0.0001) and oil content (P < 0.0001), so we assessed N and S rate effects by year and location (Tables

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7-8). For both grain yield and oil content, there were also several site-years with N x S interactions and

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those site-years trended inconsistently. Grain yield and oil content responses to N and S rate were

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inconsistent between years and locations, and there were several site-years for each with significant

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linear (N and S) and quadratic (N) effects. Inconsistency in N responses are likely due to inconsistency in

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residual soil N, in-season mineralized N, growing season atmospheric temperature and available

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water.14-15 Moreover, wheat has a high S requirement, which may obviate the need for S fertilization

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when canola is grown in rotation with wheat. In a previous study, oil content was found to decrease

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with increasing N rate (40, 60 and 80 kg N ha-1), increase with increasing S rate (0, 10, 20 and 30 kg S ha-

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1

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were inconsistent. Nitrogen studies comparing organic and inorganic fertilizer sources found an increase

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in yield in canola and wheat and a change is oil content in canola from the organic amendment perhaps

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due to slower release of N and/or adequate supply of essential micronutrients.51, 60

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) and plateau at the highest S rate.49 Oil content response to N followed this trend, but responses to S

A literature review on canola fertility noted that canola tissue N:S ratio is 12:1 at maximum

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yield.39 However, others cite recommendations that soil N:S ratio be between 5:1 and 7:1 when applying

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N and S fertilizer, but in their experiments found no relation between yield and N:S ratio when soil N

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and S levels were in the sufficient range.32 In another study, whole plant tissue N:S ranged from 1.5 to

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7.1, whereas seed N:S ranged from 7.9 to 13 in mature plants.39 In the same study, every site-year seed

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yield responded positively to N rate but S rate gave mixed results; one site-year with no S response

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surprisingly coincided with low soil test S levels but may be attributable to other limiting nutrients. The


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study thus reveals the profound effect of available water and atmospheric temperature where the

309

greatest grain yields are not necessarily obtained with the highest N and S rates. Oil content was

310

inversely related to N rate in instances where there were treatment differences indicating grain

311

partitioning to protein can happen separately from biomass accumulation.

312

In light of the overwhelming impact of available water and atmospheric temperature over N and

313

S fertility, this study underscores the need for nutrient management and crop breeding aimed at

314

adapting to weather uncertainty. There is a positive outlook for achieving those adaptations since

315

genetic diversity exists in oilseed responses to both water and temperature stress.6, 21 Crop breeding and

316

soil management that improve avoidance and/or tolerance to stress are technologies will help farmers

317

to achieve better crop productivity and quality. Expanding those technologies under a changing climate

318

will remain an important area of research.



319

Abbreviations

320 321 322

FA – fatty acid, NUE – nitrogen use efficiency, EORN – economic optimum N rate, WSU – Washington State University, TSP – triple super phosphate, H2Ot – total available water, H2Os – pre-plant root zone water, H2Op – in-season precipitation, TSDF – temperature stress during flowering


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323

Acknowledgment

324

We thank Margaret Davies, Ron Bolton, John Rumph, Dennis Pittman, Rod Rood, Aaron Esser, and Derek

325

Appel for their technical assistance.

326



327

References

328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371

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20. Aslam, M. N.; Nelson, M. N.; Kailis, S. G.; Bayliss, K. L.; Speijers, J.; Cowling, W. A., Canola oil increases in polyunsaturated fatty acids and decreases in oleic acid in drought-stressed Mediterraneantype environments. Plant Breeding 2009, 128, 348-355. 21. Aksouh-Harradj, N. M.; Campbell, L. C.; Mailer, R. J., Canola response to high and moderately high temperature stresses during seed maturation. Can J Plant Sci 2006, 86, 967-980. 22. Canvin, D. T., Effect of temperature on oil content and fatty acid composition of oils from several oil seed crops. Can J Botany 1965, 43, 63-&. 23. Knothe, G.; Van Gerpen, J. H.; Krahl, J., The biodiesel handbook. AOCS Press: Champaign, Ill., 2005; p ix, 302 p. 24. Hammac, W. A. Nutrient cycling in Pacific Northwest oilseed production. Dissertation, Washington State University, Pullman, 2015. 25. Buchanan, B. B.; Gruissem, W.; Jones, R. L., Nitrogen and Sulfur. In Biochemistry and Molecular Biology of Plants, John Wiley and Sons: Somerset, NJ, 2000; p 1367. 26. Abatzoglou, J.; Rupp, D.; Mote, P. Asymmetrical warming projections for the inland Pacific Northwest; Univ. of Idaho: 2015 27. Marschner, H., Mineral nutrition of higher plants. Academic Press: London ; Orlando, Fla., 1986; p xii, 674 p. 28. Tinker, P. B.; Nye, P. H., Solute movement in the rhizosphere. Oxford University Press: New York, 2000. 29. Barber, S. A., Soil nutrient bioavailability: a mechanistic approach. John Wiley and Sons, Inc.: New York, 1995. 30. Black, C. A., Soil fertility evaluation and control. CRC Press: New York, 1993. 31. Huggins, D. R.; Pan, W. L., Nitrogen efficiency component analysis - an evaluation of cropping system differences in productivity. Agronomy Journal 1993, 85, 898-905. 32. Karamanos, R. E.; Goh, T. B.; Poisson, D. P., Nitrogen, phosphorus, and sulfur fertility of hybrid canola. J Plant Nutr 2005, 28, 1145-1161. 33. Brennan, R. F.; Bolland, M. D. A., Comparing the nitrogen and phosphorus requirements of canola and wheat for grain yield and quality. Crop and Pasture Sci. 2009, 60, 566-577. 34. Howard, A. E.; Olson, B. M.; Cooke, S.E., Impact of soil phosphorus loading on water quality in Alberta: a review; Lethbridge, Alberta, Canada, 2006; p 41. 35. Camberato, J.; Maloney, S.; Casteel, S., Sulfur deficiency in corn. https://www.agry.purdue.edu/ext/corn/news/timeless/SulfurDeficiency.pdf (15 June 2017), 36. Lamond, R. E., Sulphur in Kansas: plant, soil and fertilizer considerations. https://www.bookstore.ksre.ksu.edu/pubs/MF2264.pdf (15 June 2017), 37. Grant, C. A.; Bailey, L. D., Fertility management in canola production. Can J Plant Sci 1993, 73, 651-670. 38. Jackson, G.; Kushnak, G.; Welty, L.; Westcott, M.; Wichman, D., Fertilizing canola. Montana AgResearch 1993, 10, 21-24. 39. Jackson, G. D., Effects of nitrogen and sulfur on canola yield and nutrient uptake. Agronomy Journal 2000, 92, 644-649. 40. Losak, T.; Vollmann, J.; Hlusek, J.; Peterka, J.; Filipcik, R.; Praskova, L., Influence of combined nitrogen and sulphur fertilization on false flax (Camelina sativa [L.] Crtz.) yield and quality. Acta Aliment Hung 2010, 39, 431-444. 41. Wetter, L. R.; Ukrainetz, H.; Downey, R. K. In Effect of chemical fertilizers on the contents of oil, protein and glucosinolates in Brassica including rapeseed, International Conference on the Science and Technology and Marketing of Rapeseed and Rapeseed Products, St. Adele, 1970; St. Adele, 1970. 42. Tkachuk, R., Nitrogen-to-protein conversion factors for cereals and oilseed meals. Cereal Chem 1969, 46, 419-423.



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43. Miller, P.; Lanier, W.; Brandt, S. Using growing degree days to predict plant stages; Montana State University Extension Service: 2001. 44. Bouchereau, A.; ClossaisBesnard, N.; Bensaoud, A.; Leport, L.; Renard, M., Water stress effects on rapeseed quality. Eur J Agron 1996, 5, 19-30. 45. Polowick, P. L.; Sawhney, V. K., High-Temperature Induced Male and Female Sterility in Canola (Brassica-Napus L). Ann Bot-London 1988, 62, 83-86. 46. Morrison, M. J.; Stewart, D. W., Heat stress during flowering in summer Brassica. Crop Sci 2002, 42, 797-803. 47. Champolivier, L.; Merrien, A., Effects of water stress applied at different growth stages to Brassica napus L var oleifera on yield, yield components and seed quality. Eur J Agron 1996, 5, 153-160. 48. Collins, F. I.; Howell, R. W., Variability of linolenic and linoleic acids in soybean oil. J Am Oil Chem Soc 1957, 34, 491-493. 49. Ahmad, G.; Jan, A.; Arif, M.; Jan, M. T.; Khattak, R. A., Influence of nitrogen and sulfur fertilization on quality of canola (Brassica napus L.) under rainfed conditions. J Zhejiang Univ Sci B 2007, 8, 731-737. 50. Nayyar, S.; Sardana, V., Growth, productivity and quality of canola and non-canola cultivars of oilseed rape (Brassica napus) as influenced by time of application of nitrogen and sulphur. J Oilseed Res 2010, 27, 123-127. 51. Gao, J.; Thelen, K. D.; Min, D. H.; Smith, S.; Hao, X. M.; Gehl, R., Effects of manure and fertilizer applications on canola oil content and fatty acid composition. Agronomy Journal 2010, 102, 790-797. 52. Tsukamoto, C.; Shimada, S.; Igita, K.; Kudou, S.; Kokubun, M.; Okubo, K.; Kitamura, K., Factors affecting isoflavone content in soybean seeds - changes in isoflavones, saponins, and composition of fatty-acids at different temperatures during seed development. J Agr Food Chem 1995, 43, 1184-1192. 53. Flagella, Z.; Rotunno, T.; Tarantino, E.; Di Caterina, R.; De Caro, A., Changes in seed yield and oil fatty acid composition of high oleic sunflower (Helianthus annuus L.) hybrids in relation to the sowing date and the water regime. Eur J Agron 2002, 17, 221-230. 54. Lapuerta, M.; Armas, O.; Rodríguez-Fernández, J., Effect of the degree of unsaturation of biodiesel fuels on NOx and particulate emissions. Int. J. Fuels Lubricants 2009, 1, 1150-1158. 55. Conley, S. P.; Tao, B., Biodiesel quality: is all biodiesel created equal? Purdue Extension Bulletin 2007. 56. Puhan, S.; Saravanan, N.; Nagarajan, G.; Vedaraman, N., Effect of biodiesel unsaturated fatty acid on combustion characteristics of a DI compression ignition engine. Biomass Bioenerg 2010, 34, 1079-1088. 57. Ackman, R. G., Chemical composition of rapeseed oil. In High and low erucic acid rapeseed oils, Kramer, J. K. G.; Sauer, F. D.; Pigden, W. J., Eds. Academic Press: Toronto, 1983; p 581. 58. Karamanos, R. E.; Harapiak, J. T.; Flore, N. A., Sulphur application does not improve wheat yield and protein concentration. Can J Soil Sci 2013, 93, 223-228. 59. Johnson, E. N.; Malhi, S. S.; Hall, L. M.; Phelps, S., Effects of nitrogen fertilizer application on seed yield, N uptake, N use efficiency, and seed quality of Brassica carinata. Can J Plant Sci 2013, 93, 1073-1081. 60. Koenig, R. T.; Cogger, C. G.; Bary, A. I., Dryland winter wheat yield, grain protein, and soil nitrogen responses to fertilizer and biosolids applications. Applied and Environmental Soil Science 2011, 2011, 1-9.

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Funding sources: WA Oilseeds Cropping Systems Project 3016, NSF IGERT Award 0903714 (NSPIRE), and

466

USDA NIFA Award no. 2011-68002-30191 (REACCH).

467



468 469 470 471 472

Figure 1: Total unsaturated fatty acid (as a percentage of total oil) response to total available water (H2Ot) and atmospheric temperature (TSDF) at two locations (Pullman, WA and Davenport, WA) and six growing seasons (2008-2013) (adjusted R2 = 0.94). Note the TSDF and H2Ot axes are reversed for ease of viewing.

473 474


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475 476 477


Figure 2: Oleic acid (as a percentage of total oil) response to total available water (H2Ot) and atmospheric temperature (TSDF) at two locations (Pullman, WA and Davenport, WA) and six growing seasons (2008-2013) (adjusted R2 = 0.57). Note the TSDF and H2Ot axes are reversed for ease of viewing.

478



479 480 481

Figure 3: Total oil response to total available water (H2Ot) and atmospheric temperature (TSDF) at two locations (Pullman, WA and Davenport, WA) and six growing seasons (2008-2013) (adjusted R2 = 0.57).

482 483 484 485


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486 487 488 489 490


Figure 4: Grain protein response to total available water (H2Ot) and atmospheric temperature (TSDF) at two locations (Pullman, WA and Davenport, WA) and six growing seasons (2008-2013) (adjusted R2 = 0.72). Note the TSDF axis is reversed for ease of viewing.

491



492 493

Figure 5: Relationship between percent protein and percent seed oil at two locations (Pullman, WA and Davenport, WA) and four growing seasons (2008-2011) (R2 = -0.69).

494


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495 496 497


Figure 6: Mitscherlich theoretical maximum grain yield response to total available water (H2Ot) and atmospheric temperature (TSDF) at two locations (Pullman, WA and Davenport, WA) and six growing seasons (2008-2013) (adjusted R2 = 0.64). Note the TSDF axis is reversed for ease of viewing.

498



499 500

Page 28 of 50

Table 1: Location, average temperature, average precipitation and soil information for study sites. Location Pullman, WA

County Whitman

Coordinates 46.76N, -117.20W

Ave. Annual Temp. 8.4°C

Ave. Annual Precip. (mm) 538

Soils

Series Palouse Thatuna Naff

Taxonomic Class Fine-silty, mixed, superactive, mesic Pachic Ultic Haploxerolls Fine-silty, mixed, superactive, mesic Oxyaquic Argixerolls Fine-silty, mixed, superactive, mesic Typic Argixerolls

Davenport, WA

Lincoln

47.66N, -118.13W

Soils

Series Broadax Hanning Mondovi

Taxonomic Class Fine-silty, mixed, superactive, mesic Calcic Argixerolls Fine-silty, mixed, superactive, mesic Pachic Argixerolls Coarse-silty, mixed, superactive, mesic Cumulic Haploxerolls

7.8°C

501 502


378

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Table 2: Soils and environmental description including crop sequence, pre-plant soil water, in-season precipitation, total water, temperature stress during flowering (TSDF), extractable inorganic N, S, P, K, pH and organic matter (OM) for each site-year. Site-year

Pullman 2008 2009 2010 2011 2012 2013

Crop sequence

Soil H2O (mm)

Precipitation (mm)

Total H2O (mm)

TSDF (days)

NO3--N/NH4+-N (kg ha-1)

S (kg ha-1)

P (mg kg-1)

K (mg kg-1)

pH

OM (%)

f-c a f-c f-c w-c w-c w-c

160 205 172 400 339 251

499 525 432 275 159 120

659 730 604 675 497 371

12 6 11 3 7 7

163 122 140 82 56 75

49 26 26 30 23 23

36 27 37 38 28 50

219 274 294 611 352 532

5.4 5.6 5.2 5.7 5.5 5.1

2.9 3.2 2.6 3.2 3.0 3.1

Davenport



2008 w-c 19 2009 f-c 250 2010 f-c 106 2011 w-c 271 2012 w-c 183 2013 w-c 179 a f-c, fallow-canola; w-c, wheat-canola

271 274 372 135 114 100

290 524 478 406 297 279

14 11 13 9 9 11

54 104 265 43 75 77


30 30 26 26 34 11

Page 30 of 50

20 13 17 15 23 17

304 442 243 401 602 465

5.8 6.0 5.5 6.2 5.7 5.7

1.7 2.0 1.3 2.2 2.8 2.2

Page 31 of 50


Table 3: Planting timing, variety, preceding crop and harvest timing for each site-year. Note fall sown winter canola was grown in 2008-2009 at Pullman. --------------------Davenport, WA---------------------Preceding Planting Variety Harvest Crop

---------------------Pullman, WA-----------------------Preceding Planting Variety Harvest Crop

Apr 2008

Hyola 357

Fallow

Aug 2008

May 2008

Hyola 357

Wheat

Aug 2008

Apr 2009

Hyola 357

Fallow

Aug 2009

Aug 2008

DKW 13-69

Fallow

Aug 2009

Apr 2010

Hyola 357

Fallow

Aug 2010

Apr 2010

Hyola 357

Fallow

Aug 2010

May 2011

DKW 55-55

Wheat

Sep 2011

May 2011

DKW 55-55

Wheat

Sep 2011

April 2012

DKW 55-55

Wheat

Aug 2012

April 2012

DKW 55-55

Wheat

Aug 2012

April 2013

DKW 55-55

Wheat

Aug 2013

April 2013

DKW 55-55

Wheat

Aug 2013



Page 32 of 50

Table 4: Model variables, parameter estimates and statistical output for Equation [3]. A is the theoretical Z-maxima, B is the efficiency factor for total available water (H2Ot), C is the efficiency factor for atmospheric temperature (TSDF), X0 is the X-intercept and Y0 is the Y-intercept. Z-Variable Unsaturated Fatty Acid Oleic Acid Total Oil Protein Mitscherlich Max Grain Yield

A 94.3 66.0 61.5 2333.7 84705. 6

B 1728.2 1242.5 1259.9 623.6

C 44.5 -22.4 28 89.3

X0 235.9 341.1 52.3 442.9

Y0 -2.0 7.4 -13.3 284.4

P-value

Water and Temperature Stresses Impact Canola (Brassica napus L

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